That's one factor that's lower-pressure (sort-of... plenty of kids end up working to help support the household, in addition to school) but still offering up similar risk & worries, on one side, and then all the bad stuff of high school and of not yet having the freedom of an adult on the other side, increasing pressure. I still think in the typical case, being a high schooler's a ton worse.
Add to this that the pressure on you in high school is in part to perform well so you don't fail at adult life. That adult life pressure, and the concerns about e.g. lack of employability or homelessness, are is already present in high school. The harm is in the future, but the pressure is already there.
Though, yes, one absolutely can "fail" badly at adult life. I don't mean to suggest it's entirely easy street. It's just a whole lot less unpleasant or difficult on average than high school.
I mean, truly, if adult life were anywhere near as harsh as high school, assuming I hadn't offed myself, I'd definitely have "failed" by now and be living on the street or something. Expectations are just... comically low, most of the time, not much-higher as so many suggested when I was in school, so it's pretty easy to do alright provided you don't get hit by bad luck (which exact same bad luck potential, again, high schoolers are exposed to via their parents anyway).